A part of feedforward and feedback antenna is adopted in offset antenna; its feed and sub-reflector are deviated from the right ahead of the reflector, which can not stop the Satellite signal, so the efficiency is high, as shown in Fig.2-5. Most offset antenna reflector shows ellipse shape or die rhombus, this antenna is often used for receiving ku band signal.

There are two kinds of offset antenna, one is once-reflected antenna, and another one is twice-reflected antenna, once-reflected antenna is the common offset antenna, as shown in Fig.2-6, also called dish antenna. Its structure is simple and cost is low, generally it is used for single Satellite receiving. Common offset antenna reflector is ellipse shape, and the diameter is 0.35m,0.45m,0.55m,0.60m,0.75m,0.85m,0.90m,1.2m,1.5m,1.8m, and so on.

Twice-reflected antenna belong to multi-curved surface antenna(multi-focus antenna), as shown in Fig.2-7, its reflector use denatured spherical surface or poraboloid, like the rectangle cut from the spherical surface, or organize the reflector by two kinds of curves, where the horizontal direction is circular arc, and vertical direction is a part of paraboloid. Thus on the antenna many feeds can be installed, and the Satellite signals can be reflected into many feeds which locates on different places, each feed can receive different Satellite signals, and so receiving different Satellites signals from one set of antenna will be realized.